Swapping uppers?

So I am in the process of building my first AR gonna go with a BCM. I also want something with a little more punch than a 5.56 for hunting whitetail. So the question is can I buy a larger caliber upper and it be compatible with my 5.56 lower? I just dont want to throw out any more cash than what I have to. Thanks for the input I am clueless when it comes to AR's other than 5.56.

So I am in the process of building my first AR gonna go with a BCM. I also want something with a little more punch than a 5.56 for hunting whitetail. So the question is can I buy a larger caliber upper and it be compatible with my 5.56 lower? I just dont want to throw out any more cash than what I have to. Thanks for the input I am clueless when it comes to AR's other than 5.56.

If its a compatible caliber. (rhetorical I know). For instance .308, No. That round has to be ar10 platform . 300 blackout, 6.8, etc. yes.

Well you have to decide on the caliber you want then see if it makes any sense buying it in an AR upper. This could be a case where a complete 30-30 lever action rifle makes more sense. Or a value priced bolt action in .308 or 30-06. These rounds are very common and easy to find.

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The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
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US Army 1966-69, VFW Life Member, Retired Geek

Well you have to decide on the caliber you want then see if it makes any sense buying it in an AR upper. This could be a case where a complete 30-30 lever action rifle makes more sense. Or a value priced bolt action in .308 or 30-06. These rounds are very common and easy to find.

Well I have a wetherby mark v 7mm-08 just thought it would be fun to have a bigger ar but the more I look and learn I don't really see a caliber I much care about having.

Biggest it gets and still be semi auto on a standard ar15 format is 458socom which at its best hits the extreme low end of 45-70 in power.

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"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith

The problem with being stupid is you cannot simply decide to stop doing dumb things...

if you really wanted to get crazy you could always buy a .50 bmg single shot bolt action upper to put on your AR lower . then you wouldnt have to take it to have it processed it would be hamburger after the shot

if you really wanted to get crazy you could always buy a .50 bmg single shot bolt action upper to put on your AR lower . then you wouldnt have to take it to have it processed it would be hamburger after the shot

I saw a semi auto 50 bmg upper where the magazine fed from the side but as always it was lots of $$$$$$$